Why phytonutrients should be everyone’s best friend.
Since starting this business my mind has been running wild trying to find new and innovative ways to provide nutrition care and information to our oncology patients. And it got me thinking… What about everyday people, like you and me, who want to improve their health and prevent the onset of cancer? As we all know, diet plays such an important role in our health and wellbeing and its impact on cancer risk is no exception! So my “inner nerd” (which many of you probably haven’t seen) decided it would be my mission to do as much research as I could to find food hacks that will help improve the health of those I love, and I thought it would be important to share with all of you too!
A topic that is very dear to my heart (in fact I’ve become obsessed with it) is a group of naturally occurring plant chemicals known as phytochemicals or phytonutrients. These guys have a range protective mechanisms for human health and I can’t wait to tell you more about them!
Now there are plenty of reasons why your Mum always told you to eat your fruit and vegetables! And here’s one… The literature suggests that diets rich in fruits, vegetables, grains, beans, legumes, herbs, spices, nuts and seeds may be protective against cancer, diabetes, cardiovascular disease, type 2 diabetes, and neurologic disorders (1, 2). Now if we dig a little deeper, it is these so called ‘phytonutrients’ that are one of the factors responsible for many of these protective health benefits. Phytonutrients are responsible for the colour and flavour of many of the fruits and vegetables we eat, e.g. the dark blue colour of blueberries or the bright orange colour of carrots. So what are these compounds and how do they have super powers you ask? Well let me tell you…
Now before I delve into the heavy stuff, I thought I would briefly explain what antioxidants are. Antioxidants are compounds which protect our cells and DNA from free radical damage (free radicals damage our cells and DNA leading to mutations and cancer). Phytonutrients are a type of antioxidant. A diet rich in antioxidants can reduce your risk of developing conditions such as cancer, heart disease, macular degeneration, neurological conditions (e.g. Parkinson’s or Alzheimer’s disease). It is important to be aware that there are thousands of phytonutrients that have been identified as having powerful properties; however there are 3 I am going to go into more detail about, specifically highlight the evidence and their effect on cancer prevention and reducing the risk of cancer recurrence.
Now I know you’re all thinking about carrots when I mention this word, and you are (somewhat) correct… Carotenoids are responsible for the bright yellow, orange and red colour in our fruit and vegetables. The bioavailability of carotenoids varies, and to optimise the absorption of these compounds it is useful to consume them in combination with fats, e.g. combining hummus dip with your carrots or adding avocado to your blueberry smoothie Common carotenoids you may have heard of include beta-carotene, alpha-carotene and lycopene and these guys are predominantly in orange, red and yellow fruit and vegetables. They are precursors for the production of Vitamin A, which is essential for our immune health and vision. Two less well known carotenoids are lutein and zeaxanthin (present in green leafy vegetables such as kale and spinach), and it is these two that are actually found in high concentration in our retinas. Therefore, it is no surprise that these less well-known carotenoids offer the greatest benefit with regard to macular degeneration (3, 4).
Now these powerful carotenoids don’t just help our vision, but they have also been shown to reduce the risk of cancer! Yup – you heard me right! A meta-analysis confirmed that total carotenoid intake was associated with a reduced risk of developing lung cancer (5) and has also shown promising evidence for those at risk of breast and prostate cancers (6, 7, 8). Our advice? Include a wide range of foods high in carotenoids e.g. carrots, pumpkin, orange, tomato, spinach and kale on the daily! If you’re thinking about using supplements, it’s essential you consult a trained medical expert first.
A large number of phytonutrients fall into this category and this group is most well known for the antioxidant rich green tea (an excellent source of cachetins). Flavonoids are naturally occurring in many fruit, vegetables, chocolate and drinks such as tea and wine. I know what you’re thinking – great let’s drink more wine and eat more chocolate! Flavonoids are highest in red wine and dark chocolate (sorry, your cadbury dairy milk and chardonnay won’t make the cut if you’re looking to increase your antioxidant intake). This doesn’t mean we should be treating ourselves daily, it’s a prompt to make better choices when you do choose to eat chocolate or drink wine.
Fruits and vegetables that are high in flavonoids include blue, purple or red berries; red and purple grapes, onions, broccoli, kale, oranges, lemons, grapefruits and soy products. Flavonoids are in a wide variety of fruit and vegetables, which is great if you’re consuming a healthy balanced diet – flavonoids on tap!
Research has shown that flavonoids have a positive impact on our cardiac health, show anti inflammatory and antithrombogenic properties, and reduce our risk of developing diabetes and cognitive conditions such as Alzheimer’s and Parkinson’s disease. Now I know what you’re thinking, what about the nasty C word? Well Dr Google tells us that drinking a cup of green tea every day will help keep cancer away. By now we should all know that Dr Google may sometimes be well-meaning, but is not always correct. The evidence here is not so clear cut. It has been hypothesised that flavonoids reduce the development and spread of cancer cells and we know this is the case in multiple animal studies (10, 11, 12), however results in human studies remain inconclusive (12, 13, 14). .
Now I may have left you pretty confused and thinking about whether you should drink that cup of green tea or not, so here’s our recommendation. If you or a loved one has a cancer diagnosis, speak to a trained medical professional about your intake of flavonoids as this will be dependant on the type of anticancer therapy you are undergoing. If you are looking to reduce your risk of developing cancer, keep sipping on that green tea as there are many other great benefits to consuming a flavonoid-rich diet. We will need to wait for some higher quality studies to come out before we give you a definitive answer on how a diet full of fabulous flavonoids will impact on the expression of our genes in the context of cancer prevention… Watch this space!
Flavenoids for you!
Now I’m going to have to really reign it in here, because this one is my favourite of all the phytonutrients!
So, where to begin… Glucosinolates are in abundance in cruciferous vegetables (broccoli, broccoli sprouts, brussel sprouts, kale, spinach, watercress, cauliflower, bok boy, cabbage, arugula and wasabi). Glucosinolates contain sulfur which is why they can taste a little bitter. Through the process of chewing or chopping these cruciferous vegetables, the glucosinolates are broken down into indoles, nitriles, thiocyanates, and isothiocyanates (sulforaphane is a member of the isothiocyanate group which is of particular interest to us and I’ll explain a bit more later on) (15). Now I know I’ve probably lost a few of you with some of the science mambo jumbo, but hang in there!!
There have been multiple animal studies which have confirmed that isothiocyanates and indoles have inhibited the development of cancer cells, specifically bladder, breast, colon, liver, lung, and stomach cancers (16, 17). Whilst human studies support the hypothesis that cruciferous vegetables are associated with decreased cancer risk, it is more challenging to differentiate if the protective effects are a result of consumption of isothiocyanates specifically or various factors associated with consumption of cruciferous vegetables.
Despite this, I thought it might be worth highlighting some interesting studies:
- A study examining fruit and vegetable intake vs prostate cancer risk found that men who consumed 3-5 servings of cruciferous vegetables per week had a 40% decrease in prostate cancer risk (18)! Now for those at risk of prostate cancer, these results speak volumes; 3-5 servings per week is easily attainable!
- Another US study showed that women who consumed greater than 5 servings of cruciferous vegetables per week significantly reduced their risk of developing lung cancer (19), again another target that is easily attainable. Now, not that I am endorsing cigarette smoking, and I most definitely don’t need to go through the evidence associated with smoking and lung cancer, however this particular study found that smokers who consumed 4.5 servings of cruciferous vegetables per MONTH (yes – per month) had a 55% reduction in lung cancer risk as a result of the anticarcinogenic effect of isothiocyanates (20).
These super phytonutrients exhibit their chemoprotective properties through protecting damage to our DNA, detoxifying our bodies from harmful carcinogens, exhibiting antibacterial, antiviral and antiinflammatory properties, inducing apoptosis (programmed cell death of nasty, unwanted cells), and inhibiting tumour spread (21). Not only has this info inspired me to increase my intake of cruciferous vegetables substantially, but it also got me thinking… What foods I can include that will give me the most concentrated form of glucosinolates possible? Which is how I formed my newest hobby… SPROUTING!
Tease all you like…sticks and stones etc etc. I’ve got my sprouts to protect me! Broccoli sprouts are rich in glucoraphanin, which is a precursor of sulforaphane (that super isothiocyanate I was talking about earlier). Sulforaphane is a particular isothiocyanate that stands out for a few reasons. As I mentioned earlier, not only does it show potent anticancer properties, it is also responsible deactivating particular enzymes that convert pro-carcinogens into active carcinogens that damages our DNA. It stops cancer in its tracks. The science speaks for itself: broccoli sprouts are safe, well tolerated and have shown no adverse effects in clinical studies (22). So I have started adding sprouts to my salads and morning smoothies and I think you should too! Just be careful if your neutropenic (low white blood cell count) after chemotherapy as they can be a bit of a food safety risk if you’re immunocompromised.
All about dem sprouts
Consuming a diet rich in fruit and vegetables can play a protective role in preventing a myriad of chronic conditions. Choosing fruit and vegetables that a full of colour and flavour will help you hit your phytonutrient targets and can optimise your health and wellbeing goals. These phytonutrients will be a weapon against many health conditions (including cancer), so be strategic and with your food choices and if you aren’t sure, contact us!
As always, if you want more information (or my broccoli sprout dealer’s digits) email, call us or make an appointment today!
T A I L O R Y O U R P L A T E | B U I L D Y O U R B E S T Y O U
Accredited Practising Dietitian
- Slavin JL, Lloyd B. Health benefits of fruits and vegetables. Adv Nutr. 2012;3(4):506-516
- He FJ, Nowson CA, Lucas M, MacGregor GA. Increased consumption of fruit and vegetables is related to a reduced risk of coronary heart disease: meta-analysis of cohort studies. J Hum Hypertens. 2007:21(9):717-728.
- Guymer RH, Chong EWT. Modifiable risk factors for age-related macular degeneration. MJA. 2006;184.
- Krinsky NI, Landrum JT, Bone RA. Biologic mechanisms of the protective role of lutein and zeaxanthin in the eye. Annu Rev Nutr. 2003;23:171-201
- Gallicchio L, Boyd K, Matanoski G, et al. Carotenoids and the risk of developing lung cancer: a systematic review. Am J Clin Nutr. 2008;88(2):372-383.
- Aune D, Chan DS, Vieira AR, et al. Dietary compared with blood concentrations of carotenoids and breast cancer risk: a systematic review and meta-analysis of prospective studies. Am J Clin Nutr. 2012;96(2):356-373.
- Vieira AR, Vingeliene S, Chan DS, et al. Fruits, vegetables, and bladder cancer risk: a systematic review and meta-analysis. Cancer Med. 2015;4(1):136-146.
- Liu H, Wang XC, Hu GH, et al. Fruit and vegetable consumption and risk of bladder cancer: an updated meta-analysis of observational studies. Eur J Cancer Prev. 2015;24(6):508-516.
- Yamane T, Nakatani H, Kikuoka N, et al. Inhibitory effects and toxicity of green tea polyphenols for gastrointestinal carcinogenesis. Cancer. 1996;77(8 Suppl):1662-1667
- Guo JY, Li X, Browning JD, Jr., et al. Dietary soy isoflavones and estrone protect ovariectomized ERαKO and wild-type mice from carcinogen-induced colon cancer. J Nutr. 2004;134(1):179-182.
- Gupta S, Hastak K, Ahmad N, Lewin JS, Mukhtar H. Inhibition of prostate carcinogenesis in TRAMP mice by oral infusion of green tea polyphenols. Proc Natl Acad Sci U S A. 2001;98(18):10350-10355.
- Romagnolo DF, Selmin OI. Flavonoids and cancer prevention: a review of the evidence. J Nutr Gerontol Geriatr. 2012;31(3):206-238.
- Cassidy A, Huang T, Rice MS, Rimm EB, Tworoger SS. Intake of dietary flavonoids and risk of epithelial ovarian cancer. Am J Clin Nutr. 2014;100(5):1344-1351.
- Amawi H, Ashby CR, Tiwari AK. Cancer chemoprevention through dietary flavonoids: what’s limiting? Chin J Cancer. 2017; 36: 50.
- Hayes JD, Kelleher MO, Eggleston IM. The cancer chemopreventive actions of phytochemicals derived from glucosinolates. European Journal of Nutrition 2008;47 Suppl 2:73-88.
- Kumar G, Tuli HS, Mittal S, Shandilya JK, Tiwari A, Sandhu SS. Isothiocyanates: a class of bioactive metabolites with chemopreventive potential. Tumour Biol. 2015;36(6):4005-4016.
- Hecht SS. Inhibition of carcinogenesis by isothiocyanates. Drug Metabolism Reviews 2000;32(3-4):395-411
- Cohen JH, Kristal AR, Stanford JL.Fruit and Vegetable Intakes and Prostate Cancer Risk. JNCI: Journal of the National Cancer Institute, Volume 92, Issue 1, 5 January 2000: 61–68.
- Feskanich D, Ziegler RG, Michaud DS, et al. Prospective study of fruit and vegetable consumption and risk of lung cancer among men and women. Journal of the National Cancer Institute 2000;92(22):1812-1823
- Tang L, Zirpoli GR, Jayaprakash V, Reid ME, Nwogu CE, Zhang Y, Ambrosone CB, Moysich KB. Cruciferous vegetable intake is inversely associated with lung cancer risk among smokers: a case-control study. BMC Cancer 2010; 10:162
- Lampe JW, Peterson S. Brassica, biotransformation and cancer risk: genetic polymorphisms alter the preventive effects of cruciferous vegetables. J Nutr. 2002;132(10):2991-2994.
- Shapiro TA, Fahey JW, Dinkova-Kostova AT, et al. Safety, tolerance, and metabolism of broccoli sprout glucosinolates and isothiocyanates: a clinical phase I study. Nutr Cancer. 2006;55(1):53-62.